Re: [Qemu-devel] [Qemu-block] [PATCH] block/vhdx: Use IEC binary prefixes from "qemu/units.h"

[Kevin Wolf]

Am 26.03.2019 um 08:55 hat Stefano Garzarella geschrieben:
> On Mon, Mar 25, 2019 at 10:56:57PM +0100, Philippe Mathieu-Daudé wrote:
> > Le lun. 25 mars 2019 21:53, John Snow <address@hidden> a écrit :
> > > On 3/21/19 5:40 AM, Stefano Garzarella wrote:
> > > > IEC binary prefixes are defined in "qemu/units.h", so we
> > > > can remove redundant definitions in "block/vhdx.h".
> > > >
> > > > Signed-off-by: Stefano Garzarella <address@hidden>
> > > > ---
> > > >  block/vhdx-log.c | 1 +
> > > >  block/vhdx.c     | 4 +++-
> > > >  block/vhdx.h     | 5 -----
> > > >  3 files changed, 4 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/block/vhdx-log.c b/block/vhdx-log.c
> > > > index 3149ff08d8..ad9905eb6d 100644
> > > > --- a/block/vhdx-log.c
> > > > +++ b/block/vhdx-log.c
> > > > @@ -18,6 +18,7 @@
> > > >   *
> > > >   */
> > > >  #include "qemu/osdep.h"
> > > > +#include "qemu/units.h"
> > > >  #include "qapi/error.h"
> > > >  #include "qemu-common.h"
> > > >  #include "block/block_int.h"
> > > > diff --git a/block/vhdx.c b/block/vhdx.c
> > > > index b785aef4b7..e9b16c5ef6 100644
> > > > --- a/block/vhdx.c
> > > > +++ b/block/vhdx.c
> > > > @@ -16,6 +16,7 @@
> > > >   */
> > > >
> > > >  #include "qemu/osdep.h"
> > > > +#include "qemu/units.h"
> > > >  #include "qapi/error.h"
> > > >  #include "block/block_int.h"
> > > >  #include "block/qdict.h"
> > > > @@ -1889,7 +1890,8 @@ static int coroutine_fn
> > > vhdx_co_create(BlockdevCreateOptions *opts,
> > > >          return -EINVAL;
> > > >      }
> > > >      if (block_size > VHDX_BLOCK_SIZE_MAX) {
> > > > -        error_setg(errp, "Block size must not exceed %d",
> > > VHDX_BLOCK_SIZE_MAX);
> > > > +        error_setg(errp, "Block size must not exceed %" PRId64,
> > > > +                   VHDX_BLOCK_SIZE_MAX);
> > >
> > > Oh, changing the constants changes the inferred type of this constant,
> > > correct?
> > >
> > 
> 
> Yes, in "units.h" all the constants are int64_t.
> 
> > Yes.
> > 
> > 
> > > >          return -EINVAL;
> > > >      }
> > > >
> > > > diff --git a/block/vhdx.h b/block/vhdx.h
> > > > index 1bfb4e4f73..deb6e362ad 100644
> > > > --- a/block/vhdx.h
> > > > +++ b/block/vhdx.h
> > > > @@ -18,11 +18,6 @@
> > > >  #ifndef BLOCK_VHDX_H
> > > >  #define BLOCK_VHDX_H
> > > >
> > > > -#define KiB              (1 * 1024)
> > > > -#define MiB            (KiB * 1024)
> > > > -#define GiB            (MiB * 1024)
> > > > -#define TiB ((uint64_t) GiB * 1024)
> > > > -
> > >
> > > I'd include units.h here because there are other references to
> > > KiB/MiB/GiB and so on throughout the rest of this header file.
> > >
> > > I think it's bad form to have a header that cannot be included unless
> > > you include other headers manually alongside it.
> > >
> > 
> > Agreed.
> 
> Okay, I'll include units.h here.
> 
> > 
> > 
> > > >  #define DEFAULT_LOG_SIZE 1048576 /* 1MiB */
> > >
> > 
> > Can we also update this definition?
> > 
> 
> Sure, I'll update it in v2.

This is used in vhdx_create_opts:

    .def_value_str = stringify(DEFAULT_LOG_SIZE),

You want the default size to be a number, not an expression, so you'd
have to change the default string to retain the number. Probably better
to just leave the #define alone.

We could, however, put a comment next to the define lik vdi.c has:

    /* Note: can't use 1 * MiB, because it's passed to stringify() */

Kevin